Question

android 怎么判断一个runnable是否被handler使用

Answer 1

/**
* Check if there are any pending posts of messages with callback r in
* the message queue.
*/
public final boolean hasCallbacks(@NonNull Runnable r) {
return mQueue.hasMessages(this, r, null);
}

Answer 2

在runnalbe的run方法里面打个标记输出一下就知道有没有被执行了。

Answer 3

千锋扣丁学堂总结：
类似Thread类，重载run方法。
Runnable mRunnable = new Runnable() {

public void run() {

//自定义功能
}

};

然后一般通过Handler，发送到消息队列里面去运行，
如 Handler mHandler = new Handler();
mHandler.post(mRunnable);
mHandler.postDelayed (mRunnable);
一些原型如下：

public final boolean post(Runnable r)
{
return sendMessageDelayed(getPostMessage(r), 0);
}

public final boolean postDelayed(Runnable r, long delayMillis)
{
return sendMessageDelayed(getPostMessage(r), delayMillis);
}

public final boolean postAtTime(Runnable r, Object token, long uptimeMillis)
{
return sendMessageAtTime(getPostMessage(r, token), uptimeMillis);
}